Kidney stones are a common disorder of the urinary tract, which are caused by a buildup of minerals in urine. While many stones pass painlessly through the urinary system, larger stones may cause debilitating pain and may have to be surgically removed. About 1 million Americans get kidney stones per year. Some of these individuals have a family history of kidney stones. The most common type of kidney stones is formed from calcium oxalate. Patients prone to kidney stone formation are typically placed on a low oxalate diet. However, patient compliance with dietary restrictions is problematic. Methods for monitoring oxalate levels in biological samples of a patient throughout the day would allow the patient to increase water consumption or reduce oxalate consumption to prevent stone formation. Such methods would also enhance patient compliance with dietary restrictions by providing almost immediate feedback on the impact of diet on oxalate levels.